1. Field of the Invention
This invention relates to a universal joint and, more particularly, to a universal joint suitable to use in a drive line of a vehicle.
2. Description of the Prior Art
One of the universal joints used in a drive line of a vehicle, is a so-called tripod type constant velocity universal joint, which comprises an inside part provided integrally with a first shaft and having three trunnions which are spaced apart circumferentially at equal intervals, an outside part disposed so as to surround the inside part, provided integrally with a second shaft and having three axially extending guide grooves which are spaced apart circumferentially at equal intervals and a roller rotatably supported by each of the trunnions to slide in one of the guide grooves. A portion of each guide groove in contact with each roller has an arcuate-shape in section and, on the other hand, each roller has an outer peripheral surface formed into a spherical surface.
When the constant velocity universal joint is incorporated in the drive line of a vehicle for use, the first and second shafts define an angle, so that the constant velocity universal joint is rotated with a so-called joint angle condition. In this case, each of the rollers will be moved relatively in an axial direction of the outside part and simultaneously in a radial direction thereof along with the rotation of the shafts. During rotation, vibrations are generated due to frictional resistance in the above relative movements to give an uncomfortable feeling to passengers.
There are various proposals to avoid the vibrations as noted above.
Japanese Utility Model Public Disclosure (KOKAI) No. 62-20225 has disclosed a universal joint, in which a portion of each guide groove of an outside part in contact with a roller has a linear shape in section, whereas the roller is formed cylindrically. A guide ring is disposed inside the roller and the roller is supported through the guide ring by a trunnion. Each of the trunnions is formed to have a spherical surface convexly extending to the guide ring which is formed to have a spherical surface convexly extending to the trunnion, and these parts are in contact with each other through respective spherical surfaces.
Japanese Patent Public Disclosure (KOKAI) No. 61-189322 discloses another universal joint, in which a portion of each guide groove of an outside part located radially outward of a roller is formed to have a linear shape in section and a roller is formed cylindrically. Between the guide groove and the roller is interposed a part U-shaped as viewed in plan, and formed to have an arcuate outer peripheral surface in section and a linear inner peripheral surface in section.
A further universal joint is disclosed in the Japanese Utility Model Public Disclosure (KOKAI) No. 61-114128, in which a plurality of needles for rotating a roller circumferentially are disposed between the roller and a trunnion and further a plurality of other needles for moving the roller axially of the trunnion are disposed inside the aforementioned needles.